Star time-chart



(No Model.)

J. B. MORSE.

STAB. TIME GHART. N0.'340,452. Patented A' 20, 1886.

WI 8838 i- I I INVENTOR ATTORNEYS.

- NITED STATES PATENT rricnt JOSEPH B. MORSE, OF BRANDON, VERMONT.

STAR TIME-CHART.

SPECIFICATION forming-part of Letters Patent No. 340,452, dated April 20, 1886.

Application filed October 27, 1885. Serial No. 181,056. (No model.)

To all whom it may concern:

Be it known that I, JosEPH B. MORSE, of Brandon, county of Rutland, Vermont, have invented a new and Improved Star Time- Ohart, of which the following is a full, clear, and exact description, reference being bad to the annexed drawings.

The object of my invention is to provide a simple apparatus for determining clock or mean time by an observation of one of the circumpolar constellations and the pole star.

My invention consists in a back piece or support having pivoted thereto a disk divided by radial lines into twelve equal spaces, representing the months of the year, the twelve spaces being subdivided to form twenty-four spaces, representing hours of the day or divisions of fifteen degrees of arc, and a movable index having its pivot coincident with that of the disk, and provided at one end with a pointer for indicating time, and at the other a represensation of one of the circumpolar constellations, preferably the Great Bear, the three parts of the apparatus being connected by a common pivot, which represents the pole star.

To the back A is pivoted a disk, B, which is divided by radial lines a into twelve spaces, b, each space representing one month of time or thirty degrees of are. The spaces b are subdivided by short radial lines o, forming with the lines a divisions of the circle representing hours. Two circles, 61 e, intersecting the lines a c, are inscribed within the periphery of the disk B, and between the circle d and the periphery of the disk, near the longer radial lines a, are written or printed the names of the months in their regular order.

On or near the lines a e, and between the circles cl 6, are printed or written figures representing the hours of the day, 12 being placed on the line a, marked November, 1 being placed on the line 0, the intermediate line in the space belonging to November, 2 being placed on the line marked October, and so on to the line for May, which is marked 12, the line cin the intermediate space helonging to May is marked 1, and on the line marked April 2 is placed, and so on around to the Novemberline,which, as before stated, is marked 12.

On the stud or rivet f, which forms the pivot of the disk B, is placed an index, D, having at one end a pointer, g, capable of moving over the graduations on the periphery of the disk, v

and at the other end an enlarged surface on which is drawn or printed the Great Bear constellation with the pointers a [1 approximately in line with the pole star, which is represented by the pivot f.

Upon the back A are formed lines It and i, radiating from the stud f, the line i being perpendicular to the straight edge j of the back, which represents the horizon.

To use my improved time-chart, the user must stand facing the pole star, and having ascertained the position of the Great Bear in the heavens the horizon-line of the chart is placed in a horizontal position and the disk B is turned so that the name of the month in which the observation is made is placed at the linei on the back A. The index D is then placed so as to bring the constellation represented thereon into the same position relative to the horizon and pivot or pole star as the constellation in the heavens bears to the natral horizon and the pole star. will now point to the hourmarked on the edge of the disk B, which will be approximately the correct mean or clock time for the time of the observation.

If it is desired to arrive at the exact time, the month-spaces may be divided up into days and the hour-spaces may be subdivided into minutes.

The movement of the disk B forward into a new position for each observation in the manner described compensates for the difference between mean and sidereal time.

Having thus described my invention, I claim as new and desire to secure by Letters Patent? The combination, with the back A, provided with radial lines it i, and the horizon-line j, of the graduated disk B, index D, having on one end a pointer and carrying at the opposite end a figure of a constellation, and a stud, f, projecting from the back and forming a common pivot for the disk B and index D, as herein specified.

JOS EPH B. MORSE.

Witnesses:

WILLIAM EOKLEY, COLLIs PLUDE.

The pointer g 

